How-to: Dealing with Mac mini Dim Video
"If anything has marred the Mac mini’s image, it is the ‘dim video’ problem. Some users with VGA monitors have reported that the video display is dark, and that whites cannot be achieved. The problem does not affect monitors connected directly using DVI. Reports are of varying magnitude—from no problem to unusable, and sites such as Macintouch and XLR8YourMac offer extensive user accounts on the problem. These reports vary in symptioms, severity and resolution, indicating that there may actually be several issues at play. To lump everything under ‘dim video’ is perhaps unfair, but that does seem to be the predominant issue."